The article by Koichi Niihara discusses the new design concept of structural ceramics, focusing on ceramic nanocomposites. These composites can be categorized into intragranular, intergranular, and nano/nano composites. The intragranular and intergranular nanocomposites significantly enhance the mechanical properties of ceramics, such as hardness, strength, toughness, and high-temperature resistance, by two to five times compared to monolithic materials. The nano/nano composites exhibit new functions like machinability and superplasticity. Niihara reviews the fabrication methods, micro- and nanostructure observations, and improvements in mechanical properties of these nanocomposites. He highlights the role of nano-size dispersoids in enhancing the properties, particularly through grain refinement, dislocation pinning, and crack deflection. The article also discusses the development of new ceramic materials by hybridizing microcomposites and nanocomposites to achieve superstrong and supertough properties. The author concludes with a new design concept for developing advanced ceramic materials, emphasizing the potential of platelet-reinforced, whisker-reinforced, and long-fiber-reinforced nanocomposites for future severe applications.The article by Koichi Niihara discusses the new design concept of structural ceramics, focusing on ceramic nanocomposites. These composites can be categorized into intragranular, intergranular, and nano/nano composites. The intragranular and intergranular nanocomposites significantly enhance the mechanical properties of ceramics, such as hardness, strength, toughness, and high-temperature resistance, by two to five times compared to monolithic materials. The nano/nano composites exhibit new functions like machinability and superplasticity. Niihara reviews the fabrication methods, micro- and nanostructure observations, and improvements in mechanical properties of these nanocomposites. He highlights the role of nano-size dispersoids in enhancing the properties, particularly through grain refinement, dislocation pinning, and crack deflection. The article also discusses the development of new ceramic materials by hybridizing microcomposites and nanocomposites to achieve superstrong and supertough properties. The author concludes with a new design concept for developing advanced ceramic materials, emphasizing the potential of platelet-reinforced, whisker-reinforced, and long-fiber-reinforced nanocomposites for future severe applications.